The Histology Core will provide training and integrated services to the researchers of individual projects. The Core will provide standard histology services, such as anesthetization and perfusion of animals prior to isolation of cochlea for immunohistochemistry and/or in situ hybridization, standard cochlear sections, and standardize histological techniques to assess damage to cochlear hair cells, as well as specialized services related to immunohistochemistry, immunocytochemistry, and in situ hybridization. The Core will further monitor developments in the field and advise researchers of emerging techniques and analytical improvements that may enhance the value of data obtained by individual projects. All methods proposed for use by the Core are already in routine use and a close working relationship exists between the investigators on the different projects and the Core Director. To further promote efficient and successful Core operation, frequent meetings will discuss progress in research, emerging techniques and assistance future directions. Furthermore, the Core will offer resources for laboratories that would like to replace their current animal models (such as the guinea pig) with mice, which offer distinct advantages by virtue of increasing availability of molecular and genetic information. Procedures are in place for scheduling and prioritization of services and quality control. The Histology Core and Physiology Core will work closely together to coordinate physiological and morphological characterization of animals under experimental conditions.